As others have said, it's a fairly straightforward interview. Expect an ATP like written test which is "semi-open book" and a sim evaluation (they place a lot of emphasis on this). Second to the sim evaluation it's going to be a few hours going through the steps together and getting to know you while you get to know the company. No gotchas, no HR panel QA sessions, just pilots trying to see if you'll fit in with the other pilots and can fly the jet. If they've called you they want to hire you, but (even as understaffed as we are) they are not doing the "fog a mirror" method.